【作者】 李学舜；

【导师】 涂赣峰； 吴文远；

【作者基本信息】 东北大学 ， 有色金属冶金， 2008， 博士

【摘要】 铈基稀土抛光粉是一种优良的抛光材料,因其独特的抛光性能及质量,而被广泛地应用于光学玻璃、电子产品等高科技领域。铈基抛光粉的抛光性能是由其特殊的物理化学性质决定的。而如何制备出性能优异的抛光粉,已经成为一项热门的研究课题。本论文以铈碳酸盐和镧铈碳酸盐为原料,通过球磨粉碎、掺氟、干燥、焙烧等工艺过程,制备出WFC型(氧化铈)、C型(含氟氧化铈)、WFLC型(镧铈氧化物)和LC型(含氟镧铈氧化物)铈基稀土抛光粉,并从晶体学的角度分析了其晶体结构,测试了其抛光性能,进而研究了晶体形貌和晶体结构与抛光性能之间的关系。论文分为四个部分：第一部分通过XRD和DTA方法对四种铈基稀土抛光粉制备流程中的粉碎过程、氟化过程、干燥过程、焙烧过程的相组成和化学反应进行了研究。并首次分别对C型(掺氟铈碳酸盐)和LC型(掺氟镧铈碳酸盐)碳酸盐焙烧过程中稀土氟氧中间化合物生成的动力学进行了研究,结果表明：其反应在357～417℃温度范围和425～452℃温度范围的动力学方程分别为y1=-4.4×102x+0.45和y2=-3.4×103x+0.69；表观活化能分别为E1=8425 kJ·mol-1,E2=65104kJ·mol-1;反应级数分别为n1=0.45和n2=0.69。第二部分采用XRD、SEM和HRTEM等测试技术对四种铈基稀土抛光粉的颗粒形貌、晶体结构(晶体尺寸、晶格常数、晶格畸变)进行了研究。结果表明：①WFC型、WFLC型铈基稀土抛光粉的烧结颗粒形貌呈片状和针状,C型和LC型铈基稀土抛光粉的烧结颗粒呈球形团聚体状态；四种铈基稀土抛光粉的颗粒都由球形晶粒组成,其中WFC型晶粒聚集紧密,WFLC型晶粒聚集紧密度仅次于WFC型,C型晶粒聚集相对松散,LC型晶粒聚集紧密度大于C型。说明F对颗粒形貌和聚集状态影响显著。②La固溶于CeO2晶格中,同时含有F时,La部分存在于CeO2晶格中形成固溶体,部分La和F共同形成新相CeLa2O3F3。③在950℃下,随焙烧时间的延长,四种铈基稀土抛光粉的晶粒尺寸均不断增大。F对CeO2的晶粒尺寸的影响大于La。同时掺La和F的铈基稀土抛光粉中的物相CeLa2O3F3将F大量固定,导致氟主要以镧铈氟氧化物存在,使得C型和LC型的CeO2晶粒的生长趋势基本一致；四种铈基稀土抛光粉中CeO2的晶格常数总的变化趋势是逐渐减小并趋于稳定,各铈基稀土抛光粉中CeO2晶格常数的大小次序为LC型>WFLC型>C型>WFC型；晶格畸变逐渐减小,F对CeO2晶格畸变的影响大于La。第三部分研究了焙烧条件、粒度分布、颗粒形貌、晶体结构(晶体尺寸和结晶子径结晶形状)与抛光粉性能之间的关系。结果表明：四种稀土抛光粉的抛光能力大小为LC型>WFLC型>C型>WFC型；950℃焙烧的LC型(含氟镧铈氧化物)稀土抛光粉的研削力、划伤和光洁度的指标都优于其他条件下制备的抛光粉；L111/L200比值太小则三级棱角十分尖锐,容易划伤工件表面；L111/L200比值太大,则三级棱角不明显,抛光能力下降,进而证明L111/L200比值接近1时抛光效果最好。第四部分采用Hunter Lab空间色体系理论,研究了以镧铈碳酸盐生产的稀土抛光粉的颜色与抛光性能的关系。其结果表明：随着焙烧温度和焙烧时间的增加,稀土抛光粉L、b值减小,a值增大,颜色逐步变深；稀土抛光粉颜色与研削能力呈规律变化。这为直接用抛光粉色度参数控制抛光粉的生产条件和评价产品质量提供了可能。更多还原

【Abstract】 The ceria-based polishing powder is a kind of outstanding polishing material. With its unique polishing performance and quality, it is extensively applied to High-tech fields, such as the optical glass, electronic product, etc. The polishing performance of ceria-based polishing powder is determined by its special physical and chemical property. And how to prepare the polishing powder of excellent performance, already become a hot subject for research.In this paper, using cerium carbonate and lanthanum-cerium carbonate as raw materials, four kinds of ceria-based rare earth polishing powders were prepared by the processes of ball milling grinding, fluorine-doping, drying and calcination.Their crystal structure were analysized, and the polishing performance were also tested.The relation between crystal structure and polishing performance were studied.This paper consists four parts:In partⅠ,the phase composition and the chemical reaction during the processes of ball milling grinding, fluorine-doping, drying and calcination were studied by XRD and DTA.And the dynamics of flu-oxide intermediate compound generating during C and LC calcinating process were studied first time.The results showed, the corresponding dynamics equation were y1=-4.4x102x+0.45,y2=-3.4×103x+0.69 respectively, and the apparent activation energy were 8425 kJ·mol-1,65104kJ·mol-1 respevtively, and the reaction order were 0.45,0.69 respevtively.In partⅡ,the particle pattern and crystal structure(consists of grain size, lattice constant and distortion of lattice) were studied by XRD,SEM and HRTEM.The results showed that: firstly, the particle patterns of WFC and WFLC ceria-based polishing powders appeared flaky and needlelike, while those of C and LC ceria-based polishing powders appeared spherical aggregate; the particle of four ceria-based polishing powders all consisted of spherical crystal grain, among which the WFC crystal grain aggregate closely, the crystal grain closeness of WFLC only was less than that of WFC, the C crystal grain aggregate incompact relatively, the crystal grain closeness of LC was higher than that of C. The above results indicated that the particle pattern and coherent condition were influenced obviously by F. Secondly, La solutionized into CeO2 crystal lattice, while in the condition that contains F simultaneously, one part of La solutionized into CeO2 crystal lattice, and the other part of La generated new phase CeLa2O3F3 with F. Thirdly, the crystal size of four ceria-based polishing powders increased with the prolonging sintering time.The effect of F on crystal size was grater than that of La. The phase CeLa2O3F3 in the ceria-based polishing powder doping La and F simultaneously fixed large quantity of F, which caused that F existed mainly as fluoxide, so the CeO2 crystal growth tendency of C and LC basically in correspondence. The general tendency of CeO2 lattice constant of four ceria-based polishing powders gradually decreased and drived to stabilization. The CeO2 lattice constant of four ceria-based polishing powders was LC>WFLC>C>WFC.The distortion of lattice gradually decreased with the prolonging time. The effect of F on the lattice distortion was grater than that of La.In partⅢ, the relation between polishing performance and many factors such as different sintering condition, size distribution,particle pattern,crystal structure(consists of grain size and crystallizing shape)were studied. The results showed that:the polishing performance of four ceria-based polishing powders was LC>WFLC>C>WFC;the polishing performance, fishtail, smooth finish of LC ceria-based polishing powder calcined under 950℃were better than others; too low L111/L200 caused tertiary edge angle to be very sharp, and work surface were easily fishtailed, while too high L111/L200 caused tertiary edge angle not to be obvious, and the polishing performance decreased, which indicated that the polishing ability was the best as the value of L111/L200 approached 1.In partⅣ, the relationship between ceria-based polishing powder’s color and the polishing performance was studied using Hunter’s Lab theory of color space. The results showed that, with the increasing calcination temperature and time, the value of L and b increased, the value of a decreased, the color became dark.The viration between the ceria-based polishing powder’s color and the polishing performance appeared regularity, so it was possible to use the color parameters to control ceria-based polishing powder’s preparing condition and evaluate the product quality.更多还原